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Tunnel junction based memristors as artificial synapses.

Thomas A, Niehörster S, Fabretti S, Shepheard N, Kuschel O, Küpper K, Wollschläger J, Krzysteczko P, Chicca E - Front Neurosci (2015)

Bottom Line: The low amplitudes of the resistance change in these types of junctions are the major obstacle for their use.Here, we increased the amplitude of the resistance change from 10% up to 100%.Utilizing the memristive properties, we looked into the use of the junction structures as artificial synapses.

View Article: PubMed Central - PubMed

Affiliation: Thin Films and Physics of Nanostructures, Bielefeld University Bielefeld, Germany ; IFW Dresden, Institute for Metallic Materials Dresden, Germany.

ABSTRACT
We prepared magnesia, tantalum oxide, and barium titanate based tunnel junction structures and investigated their memristive properties. The low amplitudes of the resistance change in these types of junctions are the major obstacle for their use. Here, we increased the amplitude of the resistance change from 10% up to 100%. Utilizing the memristive properties, we looked into the use of the junction structures as artificial synapses. We observed analogs of long-term potentiation, long-term depression and spike-time dependent plasticity in these simple two terminal devices. Finally, we suggest a possible pathway of these devices toward their integration in neuromorphic systems for storing analog synaptic weights and supporting the implementation of biologically plausible learning mechanisms.

No MeSH data available.


Related in: MedlinePlus

Typical functional layer stacks of the presented memristive tunnel junctions. The thickness of the individual layers are given in parentheses in nm.
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Figure 1: Typical functional layer stacks of the presented memristive tunnel junctions. The thickness of the individual layers are given in parentheses in nm.

Mentions: In this manuscript, we will present several oxides used as the barrier materials in tunnel junctions. A cartoon of the layer stacks is depicted in Figure 1. Many oxides can exhibit memristive switching behavior in such a tunneling structure, which allows us to tailor the electrode and barrier materials for a given application. First, we introduce magnesia based tunnel junctions and use them to look into the analogs of long-term potentiation, long-term depression, and spike-time dependent plasticity, which are the basic functional properties of biological synapses (Thomas, 2013). However, the resistance change in these junctions is rather small [(Rmax − Rmin)/Rmin = 8%]. Consequently, new material combinations are tested, and we will show resistive switching in BaTiO3 and Ta-O based systems. BaTiO3 and TaO based junctions exhibit up to 10 times larger resistance changes, which improves the prospects of these systems in semiconductor-based neuromorphic circuits. The general suitability of these junctions is discussed in the last section and compared to the requirements suggested by Indiveri et al. (2013).


Tunnel junction based memristors as artificial synapses.

Thomas A, Niehörster S, Fabretti S, Shepheard N, Kuschel O, Küpper K, Wollschläger J, Krzysteczko P, Chicca E - Front Neurosci (2015)

Typical functional layer stacks of the presented memristive tunnel junctions. The thickness of the individual layers are given in parentheses in nm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493388&req=5

Figure 1: Typical functional layer stacks of the presented memristive tunnel junctions. The thickness of the individual layers are given in parentheses in nm.
Mentions: In this manuscript, we will present several oxides used as the barrier materials in tunnel junctions. A cartoon of the layer stacks is depicted in Figure 1. Many oxides can exhibit memristive switching behavior in such a tunneling structure, which allows us to tailor the electrode and barrier materials for a given application. First, we introduce magnesia based tunnel junctions and use them to look into the analogs of long-term potentiation, long-term depression, and spike-time dependent plasticity, which are the basic functional properties of biological synapses (Thomas, 2013). However, the resistance change in these junctions is rather small [(Rmax − Rmin)/Rmin = 8%]. Consequently, new material combinations are tested, and we will show resistive switching in BaTiO3 and Ta-O based systems. BaTiO3 and TaO based junctions exhibit up to 10 times larger resistance changes, which improves the prospects of these systems in semiconductor-based neuromorphic circuits. The general suitability of these junctions is discussed in the last section and compared to the requirements suggested by Indiveri et al. (2013).

Bottom Line: The low amplitudes of the resistance change in these types of junctions are the major obstacle for their use.Here, we increased the amplitude of the resistance change from 10% up to 100%.Utilizing the memristive properties, we looked into the use of the junction structures as artificial synapses.

View Article: PubMed Central - PubMed

Affiliation: Thin Films and Physics of Nanostructures, Bielefeld University Bielefeld, Germany ; IFW Dresden, Institute for Metallic Materials Dresden, Germany.

ABSTRACT
We prepared magnesia, tantalum oxide, and barium titanate based tunnel junction structures and investigated their memristive properties. The low amplitudes of the resistance change in these types of junctions are the major obstacle for their use. Here, we increased the amplitude of the resistance change from 10% up to 100%. Utilizing the memristive properties, we looked into the use of the junction structures as artificial synapses. We observed analogs of long-term potentiation, long-term depression and spike-time dependent plasticity in these simple two terminal devices. Finally, we suggest a possible pathway of these devices toward their integration in neuromorphic systems for storing analog synaptic weights and supporting the implementation of biologically plausible learning mechanisms.

No MeSH data available.


Related in: MedlinePlus